Autoimmune inner ear disease (AIED), or idiopathic, progressive, bilateral, sensorineural hearing loss (IPBSNHL), is a rapidly progressive form of sensorineural deafness that occurs over weeks to months and affects both ears, usually asymmetrically. To date, no correlation has been made relative to age, gender, race, or ethnicity. Researchers believe that IPBSNHL is caused by inflammation and is triggered by an autoimmune process. Treatment has aimed at suppression or control of these processes with anti-inflammatory drugs. Prednisone, methotrexate and cyclophosphamide are approved by the FDA for treatment of some autoimmune conditions, but not for the treatment of IPBSNHL. The AIED study is a multicenter clinical trial with the overall goals of identifying and quantifying the role of prednisone, methotrexate and cyclophosphamide in reversing or preventing hearing loss among individuals diagnosed as having IPBSNHL. The trial has two phases. Phase 1 involves all enrolled participants and consists of a one-month regimen of prednisone therapy (60 mg/day). At the end of Phase 1, the impact of prednisone therapy will be assessed via standardized audiometric measures. Participants who demonstrate improved hearing, will be enrolled in a blinded randomized clinical trial of methotrexate versus placebo therapy (Phase 2a). Participants whose hearing does not improve, will be tapered from prednisone and will continue to be followed (Phase 2b). Participants who experience worsening hearing loss during Phase 1 or Phase 2b may be enrolled in an open-label randomized trial of methotrexate versus cyclophosphamide (Phase 2c). The primary study objectives are as follows:1) to examine whether prescription of methotrexate treatment in participants with IPBSNHL who respond initially to high dose prednisone (60mg/day) will maintain the hearing gains developed while on prednisone therapy (Phase 2a), 2) to describe the experience of those persons whose hearing does not improve after one month of prednisone therapy as they undergo prednisone tapering and cease prednisone therapy (phase 2b): and 3) to describe the efficacy and toxicity of cyclophosphamide and methotrexate therapy in a subset of IPBSNHL participants whose hearing loss continues during a one month prescription of prednisone therapy or whose hearing loss resumes during and after the prednisone tapering of Phase 2b (Phase 2c).The secondary study objectives are as follows:1) to identify the proportion of IPBSNHL participants who are responsive to prednisone therapy (60mg/day): and 2) to determine the laboratory and clinical risk factors for the prediction of therapeutic outcomes among participants with IPBSNHL.The AIED study participants will be between the ages of 18 to 70 years of age. Study participants must be able to comprehend and speak English or Spanish in order to perform the audiometric word identification tests. The ability to write or read English or Spanish is not necessary.